A hypodermic syringe is used to inject fluids into or draw fluids from animal and human bodies. The syringe has a cylindrical barrel with a needle attached to one end and a plunger partly disposed in the other end. When purchased, all of the parts of a disposable syringe are sterile and arrive in sterile packaging. The needle itself is usually also shielded with a protective cap.
Typically, after inserting the syringe needle into the patient for an injection, the user adjusts his grip so that his second and third fingers fit under a flange on the syringe barrel and his thumb rests on top of the plunger. The plunger is then pressed into the syringe barrel by the user's thumb while the second and third fingers press against the flange. The resulting forward movement of the plunger forces medicine through the needle and into the patient.
Contamination of a hypodermic needle, which results from contact with human or animal tissues, blood, or other bodily fluids, may be dangerous when it contains infectious organisms. Health care workers have developed serious infections from accidental punctures or scrapes, collectively termed "needle sticks".
After use of a syringe, the original protective cap may be replaced to eliminate the risk of an accidental needle stick. However, this has proven to be hazardous. To cover the needle with a protective cap, one hand must hold the syringe with one hand while using the other hand to place the protective cap over the needle. If the user fails to insert the needle into the cap, he may accidentally puncture his other hand.
In emergencies, the likelihood of suffering a needle stick is even greater. The health care worker is faced with two options, either to quickly attempt to shield the needle with a protective cap, increasing the risk of a needle stick, or to leave the contaminated needle exposed as a threat to other workers in the environment. Neither alternative is desirable. Indeed, recognizing the risk recapping imposes, some health care facilities recommend that their workers not attempt to recap contaminated needles.
Disposal containers for syringes, used by some health care workers, have achieved minimal success in eliminating the risk of a needle stick. As with protective caps, disposal containers are often lost or are simply out of reach when needed. Additionally, the use of disposal containers has proven to be cumbersome.
Manually operated protective sheaths, developed to eliminate the risks of accidental puncture, have also been proposed. Typically, these protective sheaths, which are cylindrical in shape, are slidably mounted over the syringe barrel. As with the other protective arrangements discussed above, both hands are needed. While holding the syringe in one hand, the user's other hand must reach for the sheath and then slidably engage and lock the sheath over the needle. If the user is hurried or careless when reaching for the sheath, he may incur a needle stick.
Accordingly, it is a principal object of this invention to provide a hypodermic syringe with a protective sheath which can be readily deployed with one hand.
Another object of the invention is to provide a syringe with a protective sheath that effectively prevents needle sticks when it is deployed.
A further object is to provide a syringe with a protective sheath that may be in its deployed position to maintain protection from needle sticks during subsequent handling of the syringe.
Another object of this invention is to provide a syringe with a protective sheath that permits use of measurement indicia on the syringe barrel.